Use EapMethod to provide correct network error message

BUG=297374
R=pneubeck@chromium.org

Review URL: https://codereview.chromium.org/24644005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226246 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226246